COPENHAGEN, Denmark (AP) — Sweden's postal service was puzzled when packages of electronics disappeared from its trucks on a road northeast of Goteborg, the country's second-largest city.

PostNord head of security Alexis Larsson says they mounted concealed cameras inside the back of a postal truck in September to crack the thefts, which were estimated to be worth 2.5 million kronor (about $300,000).

Larsson said Friday he was astounded as he watched two men leap onto the moving truck from the hood of a car traveling behind it, enter the cargo area and rummage through the load. He says the truck was going 80 kph (50 mph) when the thieves boarded it.

He says police were contacted and four men — all non-Swedes — were arrested on Sept. 16.